Compounds having a carbonyl group are important in industrial fields. Examples of known methods for producing a carbonyl compound by using an oxidation reaction include a method of oxidizing alcohols with chromic acid, a method of oxidizing by using tetrapropylammonium perruthenate as a catalyst, Swern oxidation, and Dess-Martin oxidation. However, from the viewpoint that toxic chrome is required in a stoichiometric amount, N-methylmorpholine oxide used as a co-oxidizing agent for oxidation with the use of tetrapropylammonium perruthenate as a catalyst is expensive, malodorous dimethyl sulfide or toxic carbon monoxide is produced as a by-product during Swern oxidation, and the Dess-Martin reagent has a risk of explosion during the synthesis, or the like, there is a demand for a chemical synthesis technique that is more environmentally friendly and can be carried out at a low cost. An example of such a chemical synthesis method is a dehydrogenation oxidation reaction using a catalyst. According to the reaction of method, it is unnecessary to use a toxic metal in a stoichiometric amount and an expensive co-oxidizing agent, and there are no problems of having malodor and risks originating from a by-product. As an example of the reaction, Oppenauer oxidation which uses aluminum isopropoxide as a catalyst and acetone or the like as a hydrogen acceptor is known. However, this reaction is disadvantageous in that the catalyst efficiency is not good and, although oxidation of secondary alcohols into ketones can be easily carried out, an application to other dehydrogenation oxidation reaction is difficult to achieve. As such, there is a demand for a catalytic reaction with high efficiency.
Examples of the catalyst having good efficiency include a ruthenium complex.
Examples of the method of producing a carbonyl compound by using a ruthenium complex as a dehydrogenation oxidation catalyst include the production of aldehydes from primary alcohols, the production of ketones from secondary alcohols, the production of esters from two molecules of alcohols, the production of esters from aldehydes and alcohols, the production of lactones from diols, the production of amides from alcohols and amines, the production of amides from aldehydes and amines, and the production of lactams from aminoalcohols.
As a method of producing aldehydes from primary alcohols that are represented by the following reaction general formula (1) by using a ruthenium complex as a dehydrogenation oxidation catalyst,
(in the formula, RN1 represents a hydrogen atom or a monovalent organic group).a method of using the ruthenium-μ-oxo-μ-hydroxo complex represented by the following chemical formula (2) which is described in Non Patent Literature 11
(in the formula, Cy represents a cyclohexyl group)or the heterobimetallic rhodium-ruthenium complex represented by the following chemical formula (3) which is described in Non Patent Literature 14 is known.
(in the formula, Ph represents a phenyl group)
However, with respect to the ruthenium-μ-oxo-μ-hydroxo complex disclosed in Non Patent Literature 11, only benzyl alcohols or aryl alcohols were used as a primary alcohol, which is a reacting compound. Further, as a primary alcohol that can be used for production of an aldehyde with good yield with the use of the heterobimetallic rhodium-ruthenium complex disclosed in Non Patent Literature 14, benzyl alcohols can be mentioned. However, it is also reported that the yield is lowered when 1-alkanol is used.
Further, to obtain conversion ratio at sufficient level, 2.5 mol % of the catalyst (as being a tetranuclear complex, it is 10 mol % in terms of ruthenium) is required for the ruthenium-μ-oxo-μ-hydroxo complex disclosed in Non Patent Literature 11, and the hetero bimetallic rhodium-ruthenium complex containing expensive rhodium is used in an amount of 0.5 mol % according to the method disclosed in Non Patent Literature 14.
Further, as a method of producing ketones from secondary alcohols that are represented by the following reaction general formula (4) by using a ruthenium complex as a dehydrogenation oxidation catalyst
(in the formula, RN2 and RN3 each independently represent a hydrogen atom or a monovalent organic group), a method of using the ruthenium-diphosphine-diamine complex represented by the following chemical formula (5) which is disclosed in Non Patent Literature 1,
(in the formula, Ph represents a phenyl group)a catalyst using the carbonyl tris(triphenylphosphine) ruthenium (II) dihydride disclosed in Non Patent Literature 10 in combination with diphosphine,the ruthenium-μ-oxo-μ-hydroxo complex represented by above chemical formula (2) which is disclosed in Non Patent Literature 11, the ruthenium-ferrocenyl oxazolinyl phosphine complex represented by the following chemical formula (6) which is disclosed in Non Patent Literature 15,
(in the formula, R represents an isopropyl group or a phenyl group)the ruthenium-arene-diamine complex represented by the following chemical formula (7) which is disclosed in Non Patent Literature 16,
(in the formula, Ts represents a p-toluene sulfonyl group, Ar represents p-cymene or mesitylene, and Ph represents a phenyl group)the binuclear ruthenium complex represented by the following chemical formula (8) which is disclosed in Non Patent Literature 17,
(in the formula, Ph represents a phenyl group)or the tris(triphenylphosphine)ruthenium (II) dichloride complex which is disclosed in Non Patent Literature 18 is known.
However, with respect to the ruthenium-diphosphine-diamine complex disclosed in Non Patent Literature 1, the oxidation yield of acetophenone is only 58% after 20 hours even when 0.4 mol % of catalyst is used.
Further, the catalyst disclosed in Non Patent Literature 10 in which the carbonyl tris(triphenylphosphine) ruthenium (II) dihydride and diphosphine are used in combination requires the use of 1.25 to 2.5 mol % of catalyst and 24 hours of reaction time.
Further, although it is described that the ruthenium-μ-oxo-μ-hydroxo complex described in Non Patent Literature 11 has the same catalytic activity even after being re-used five times, since 2.5 mol % of the complex is used for single reaction (as being a tetranuclear complex, it is 10 mol % in terms of ruthenium), 0.5 mol % of the catalyst (as being a tetranuclear complex, 2 mol % in terms of ruthenium) is required when it is re-used five times.
Further, the ruthenium-ferrocenyl oxazolinyl phosphine complex disclosed in Non Patent Literature 15 requires a multi-step for synthesis of a ligand as described in Synlett., 1995, p 74-76 or Synlett., 1995, p 79-80, and therefore it is cumbersome to carry out and has poor yield.
Further, the ruthenium-arene-diamine complex disclosed in Non Patent Literature 16 requires the use of an optically active and expensive diamine ligand and the catalyst is required in amount of 0.2 mol %.
The binuclear ruthenium complex disclosed in Non Patent Literature 17 requires at least 20 hours of reaction time for many substrates when the catalyst is used in an amount of 0.1 mol %. Further, when cyclohexanol is used as a substrate, for example, the yield was only 60% after 24 hours.
The tris(triphenylphosphine)ruthenium (II) dichloride complex disclosed in Non Patent Literature 17 requires acetophenone as an additive for oxidation of 2-octanol, for example. Further, the yield was only 60% or so after 12 hours of reaction. Further, although a method of using the tris(triphenylphosphine)ruthenium (II) dichloride complex is also disclosed in Non Patent Literature 18, the yield was 71% after 24 hours of reaction when it was used in an amount of 0.2 mol %.
Further, as a method of producing esters from two alcohol molecules that are represented by the following reaction general formula (9) by using a ruthenium complex as a dehydrogenation oxidation catalyst
(in the formula, RN4, RN5, RN6, and RN7 each independently represent a hydrogen atom or a monovalent organic group), a method of using the ruthenium-carbonyl complex represented by the following chemical formula (10) which is disclosed in Non Patent Literature 6,
the ruthenium-carbonyl complex represented by the following chemical formula (11), chemical formula (12), or chemical formula (13) that are disclosed in Non Patent Literature 13
(in the formula, iPr represents an isopropyl group)
(in the formula, tBu represents a tert-butyl group and Et represents an ethyl group)
(in the formula, tBu represents a tert-butyl group and Et represents an ethyl group)or the tetrakis(triphenylphosphine) ruthenium (II) dihydride complex which is disclosed in Non Patent Literature 19 is known.
However, with the ruthenium-carbonyl complex disclosed in Non Patent Literature 6, 26 to 72 hours of reaction time was required to have sufficient yield.
Further, to synthesize a ligand for the ruthenium-carbonyl complex represented by the chemical formula (11) which is disclosed in Non Patent Literature 13, extremely low temperature like −90 degrees C. is required as described in Organometallics, 2003, 22, p. 4604-4609, for example. To synthesize a ligand for the complex represented by the chemical formula (12) and the chemical formula (13), environmentally unfriendly carbon tetrachloride or extremely low temperature like −78 degrees C. is required.
Further, as a method of producing esters from aldehydes and alcohols that are represented by the following reaction general formula (14) by using a ruthenium complex as a dehydrogenation oxidation catalyst
(in the formula, RN8, RN9, RN10, and RN11 each independently represent a hydrogen atom or a monovalent organic group), a method of using the ruthenium-carbonyl complex represented by above chemical formula (13) which is disclosed in Non Patent Literature 13 or the tetrakis(triphenylphosphine) ruthenium (II) dihydride complex which is disclosed in Non Patent Literature 19 is known.
However, to synthesize a ligand for the ruthenium carbonyl complex having a pyridine ring, one phosphino group, and one tertiary amine group as described in Non Patent Literature 13, environmentally unfriendly carbon tetrachloride or extremely low temperature like −78 degrees C. is required.
Further, according to the method of using the tetrakis(triphenylphosphine) ruthenium (II) dihydride complex which is disclosed in Non Patent Literature 19, it is required to have 24 hours of reaction time with the use of a catalyst in an amount of 5 mol %.
Further, regarding a method of producing lactones from diols that are represented by the following reaction general formula (15) by using a ruthenium complex as a dehydrogenation oxidation catalyst,
(in the formula, QN1-XN1-QN2 represents a divalent organic group), they can be produced with high efficiency by using the ruthenium-phosphine-diamine complex represented by the following general formula (16) which is disclosed in Non Patent Literature 12.
(in the formula, Me represents a methyl group).
Further, a method of using the tetrakis(triphenylphosphine) ruthenium (II) dihydride complex which is described in Non Patent Literature 19 or a method of using the Cp*RuCl(Ph2P(CH2)NH2) complex which is described in Non Patent Literature 20 is known.
However, according to the method of using the ruthenium-phosphine-diamine complex which is disclosed in Non Patent Literature 12, it is required to have 48 hours under high temperature condition like 200 degrees C. or more to complete the reaction by using it in an amount of 0.0058 mol %.
Further, according to the method of using the tetrakis(triphenylphosphine) ruthenium (II) dihydride complex which is disclosed in Non Patent Literature 19, it is required to use 2 mol % of the catalyst.
Further, according to the method of using Cp*Ru(PN) complex which is disclosed in Non Patent Literature 20, it is required to use 1 mol % of the catalyst.
Further, as a method of producing amides from amines and alcohols that are represented by the following reaction general formula (17) by using a ruthenium complex as a dehydrogenation oxidation catalyst,
(in the formula, RN12, RN13, and RN14 each independently represent a hydrogen atom or a monovalent organic group)(1) a method of using the ruthenium N-heterocyclic carbene complex as disclosed in Non Patent Literature 3, (2) a method of using the tetrakis(triphenylphosphine) ruthenium dihydride complex, N-heterocyclic carbene precursor, sodium hydride, and acetonitrile as disclosed in Non Patent Literature 4, (3) a method of using the ruthenium N-heterocyclic carbene complex as disclosed in Non Patent Literature 5, (4) a method of using arene ruthenium (II) chloride dimer complex, N-heterocyclic carbene precursor, sodium hydride, and acetonitrile or pyridine as disclosed in Non Patent Literature 7, (5) a method of using the dichloro(1,5-cyclooctadiene)ruthenium (II), N-heterocyclic carbene precursor, potassium tert-butoxide, and phosphine ligand as disclosed in Non Patent Literature 8, and (6) a method of using the ruthenium carbonyl complex having a pyridine ring, one phosphino group, and one tertiary amino group that is represented by above chemical formula (13) as disclosed in Non Patent Literature 9 are known.
However, the method disclosed in Non Patent Literature 3, 4, 5, 7, and 8 requires the use of 5 mol % catalyst.
Further, to synthesize a ligand for the ruthenium carbonyl complex having a pyridine ring, one phosphino group, and one tertiary amino group as disclosed in Non Patent Literature 9, environmentally unfriendly carbon tetrachloride or extremely low temperature like −78 degrees C. is required.
Further, as a method of producing amides from amines and aldehydes that are represented by the following reaction general formula (18) by using a ruthenium complex as a dehydrogenation oxidation catalyst,
(in the formula, RN15, RN16, and RN17 each independently represent a hydrogen atom or a monovalent organic group)(1) a method of using the tetrakis(triphenylphosphine) ruthenium dihydride complex, N-heterocyclic carbene precursor, sodium hydride, and acetonitrile as disclosed in Non Patent Literature 4, (2) a method of adding the ruthenium N-heterocyclic carbene complex and 10 mol % of primary alcohol as disclosed in Non Patent Literature 5, and (3) a method of using arene ruthenium (II) chloride dimer complex, N-heterocyclic carbene precursor, sodium hydride, and acetonitrile or pyridine as disclosed in Non Patent Literature 7 are known.
However, according to a method of using the tetrakis(triphenylphosphine) ruthenium dihydride complex, N-heterocyclic carbene precursor, sodium hydride, and acetonitrile as disclosed in Non Patent Literature 4, the method of adding the ruthenium N-heterocyclic carbene complex and 10 mol % of primary alcohol as disclosed in Non Patent Literature 5, or the method of using ruthenium, N-heterocyclic carbene precursor, a base, and acetonitrile or pyridine as disclosed in Non Patent Literature 7, 5 mol % of the catalyst and the reaction time of 24 to 36 hours are required.
Further, as a method of producing amides from aminoalcohols that are represented by the following reaction general formula (19) by using a ruthenium complex as a dehydrogenation oxidation catalyst
(in the formula, RN18 represents a hydrogen atom or a monovalent organic group, the QN3-XN2-QN4 represents a divalent organic group), a method of using the ruthenium-diphosphine-diamine complex represented by the following chemical formula (20) which is disclosed in Non Patent Literature 2,
(in the formula, Ph represents a phenyl group), a method of using the ruthenium N-heterocyclic carbene complex which is disclosed in Non Patent Literature 3, and a method of using the ruthenium N-heterocyclic carbene complex which is disclosed in Non Patent Literature 5 are known.
However, with respect to the ruthenium-diphosphine-diamine catalyst which is disclosed in Non Patent Literature 2, the catalyst is required in an amount of 2.5 mol % to obtain sufficient conversion ratio.
Further, with respect to the ruthenium N-heterocyclic carbene complex which is disclosed in Non Patent Literature 3 and Non Patent Literature 5, the catalyst is required in an amount of 5 mol %.